"Until very recently, all indications were that this magnetar had one of the weakest surface magnetic fields known; at 6 x 1012 Gauss, it was roughly a 100 times lower than for typical magnetars,” said Andrea Tiengo, lead author of the paper, in a statement.

"Understanding these results was a challenge. However, we suspected that SGR 0418 was in fact hiding a much stronger magnetic field, out of reach of our usual analytical techniques."

Normally, scientists determine the magnetic field of a magnetar by measuring the rate at which the star's spin is declining, but for SGR 0148, researchers searched for variations in the X-ray spectrum of the magnetar over short time intervals.

"This method allows astronomers to analyse the magnetic field in much more detail and has revealed SGR 0418 as a true magnetic monster," ESA writes.